LED lamp has gradually become a new generation of illuminations because of advantages such as low energy consumption, energy-saving, fast response and longer service life etc. However, dimming controlling for LED lamp is still a realistic problem.
The current dimming technology for LED lamp includes linear dimming, PMW (Pulse Width Modulation) dimming and silicon controlled dimming, all of which are realized by adding some circuits inside driving chips of the LED and adding peripheral components cooperating with the circuits. For example, the linear dimming may be realized by adjusting an adjustable resistances and the PMW dimming may be realized by adding some PMW chips, both of which need adding some extra components. Although the silicon controlled dimming may replace incandescent lamps or halogen lamps by LED lamps, it works under a chopped wave mode and an output voltage may not be a sine wave and thus a lot of harmonic waves may be created and may cause serious damages to a power grid.
Since the above-mentioned methods of dimming need adding extra components outside chips, structures of the lamps may be complicated, manufacture costs may be high, and operations of the lamps may be inconvenient.